This invention relates to patient monitoring systems and particularly to patient monitoring systems in which movement of a patient beyond a certain distance provides an alarm or a warning.
In one class of patient monitoring system, a fastener is connected to a monitoring housing by a cord or other device having a fixed length so that if the fastener moves beyond that length, the monitoring housing is activated. The fastener is connected to a patient such as to the clothing of a patient by a clip so that, if the patient moves beyond a fixed distance such as by slumping from a wheelchair onto the floor or moving from a bed, the monitoring housing provides an alarm.
In a prior art monitoring system of this type, the end of the cord opposite to the fastener is loosely fitted into the monitoring housing so that, when the patient moves away from the monitoring housing a distance greater than the length of the cord, that end is pulled free. When the end is pulled free from the monitoring housing, an alarm is given. Prior art systems of this type are disclosed in U.S. Pat. Nos. 4,577,185, 4,858,622, and 4,583,084 and systems of this type are on sale under the trademark, TABS, by Wanderguard, Inc., a division of Senior Technologies, Inc., located at 941 "0"Street, Suite 205, Lincoln, Neb. 68508.
This type of prior art patient monitoring system has several disadvantages, such as for example: (1) from time to time the fastener falls loose from the patient or is removed by the patient so that the system fails; and (2) the patient may hear or see the alarm and be unduly excited by it or the patent may not hear the alarm but continue to leave the bed or chair to which the patent is confined.
Spring loaded fasteners are known in the prior art and are generically referred to as alligator clips. At least one type of prior art alligator clip provides an electrical signal when closed. Such an alligator clip is disclosed in U.S. Pat. No. 4,616,113 as part of a fabric theft warning device. This prior art alligator clip with a sensor is relatively expensive because it has a special mechanism to prevent a thief from slipping a card between the jaws of the alligator clip when the fabric is removed and thus being able to remove the fabric without giving the alarm.